The latest 7.4.1 update for Time Capsule and Airport Extreme adds Back to My Macdrive sharing, which lets you grab files off of attached USB drives over the internet.

The Back to My Mac is only for MobileMe users, and Airport Express remains unchanged, but if you're looking forward to being able to access a bunch of files easily while you're at work/home/somewhere else, it's pretty handy. [Apple Insider]